The Great Space Race ... With Clocks

Short Wave

NPR

Daily News, Nature, Life Sciences, Astronomy, Science, News

4.7 • 6K Ratings

🗓️ 26 May 2025

⏱️ 16 minutes

🔗️ Recording | iTunes | RSS

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Summary

Happy Memorial Day, Short Wavers! This holiday, we bring you a meditation on time ... and clocks. There are hundreds of atomic clocks in orbit right now, perched on satellites all over Earth. We depend on them for GPS location, Internet timing, stock trading and even space navigation. In today's encore episode, hosts Emily Kwong and Regina G. Barber learn how to build a better clock. In order to do that, they ask: How do atomic clocks really work, anyway? What makes a clock precise? And how could that process be improved for even greater accuracy?

- For more about Holly's Optical Atomic Strontium Ion Clock, check out the OASIC project on NASA's website.
- For more about the Longitude Problem, check out Dava Sobel's book, Longitude.

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Transcript

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0:00.0	This message comes from Nature on PBS, producers of Going Wild with Dr. Ray Wynn-Grant.
0:06.4	Back for a brand new season, Going Wild highlights champions of nature and what led them to create change within themselves and the natural world.
0:15.8	Follow Going Wild wherever you get your podcasts.
0:19.6	You're listening to Shortwave from NPR.
0:27.0	Hey, everyone, Regina Barber here with Emily Kwong and a story about time.
0:31.8	Yes, a tale about how time tells us our place in the world.
0:36.0	So, Gina, are you familiar with longitude? Yeah, so
0:38.6	longitude is like the east-west position on earth. It's relative to the prime meridian in Greenwich,
0:44.5	England, right? Yeah, the longitude there is zero degrees and extends by 180 degrees westward
0:49.8	and 180 degrees eastward. And back in the 1600s, it was really difficult to calculate longitude.
0:56.6	A ship leaving port would set two clocks.
0:59.3	One for the prime meridian and another for local time.
1:02.3	So crews would update their local time as they sailed, calculating it by using the position of the sun.
1:08.0	And by knowing the difference between these two times, you can calculate, like,
1:11.1	the in-between longitudinal degrees and know your location.
1:14.5	Yeah, you can math.
1:15.6	Right.
1:16.1	But the clocks aboard these ships were not reliable.
1:19.4	Like, picture pendulum clocks on rolling seas, right?
1:22.7	Surrounded by salty air and changes in temperature or barometric pressure.
1:30.3	The clock parts are going to warp. All of us can ultimately cause the clock to stray from the correct time.
1:33.3	We call this clock drift.
	...

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